This invention relates to a drive suitable for use with the magnetic tapes utilized in small-size recording apparata, e.g. cassette tape recorders.
The magnetic tape is known to run in a tape recorder at a constant and pre-determined rate whenever the recorder is operated either in the recording mode or in the playing mode, whereas during fast rewinding or fast advancing the tape runs at a much higher rate. Furthermore, during the latter modes of operation, the tape moves in opposite directions, since in the fast forward or fast advance condition the tape is wound around the take-up reel, whereas in the rewind condition the tape is wound around the pay-out reel. Since all the moving parts inside a tape recorder of the medium or small size types are driven by a single electric motor operating at a substantially constant speed and rotating always in one direction, the prior art approach has been based upon the provision of manually operated and fairly complicated gear and lever systems for an appropriate conversion of the motion imparted by said motor. A detailed description of a conventional moving wheel and linkage system is not provided herein, as such systems are well known to the expert and would involve an extensive discussion. It should suffice to mention that, for example, the motor is connected through a drive belt to a flywheel affixed coaxially to a stub shaft the peripheral speed whereof exactly matches the desired rate of advance of the tape when being recorded or played. Said flywheel, in turn, contacts movable wheels which, according to their positioning as determined manually by depressing the fast forward or rewind keys or buttons, bring the flywheel in further contact with disc elements which are coaxial to the drive spindle wherearound the tape coils and decoils. Said wheels are sized and arranged such that the rotational movement imparted by the flywheel to said drive spindles has a speed much higher than said stub shaft, and moreover reverses its direction depending on whether it is transferred to the forward shaft or rewind shaft.
It will be apparent that all this involves of necessity the manufacture and installation of an appreciably high number of precision matched components, which have to be very accurately assembled because any unreliable contact between the wheels would reflect in the magnetic tape coming to a stop. Consequently, the recorder manufacturing cost is high and the manufacturing process thereof long and complex. Another drawback is to be found in the increased overall dimensions resulting from such drives, and grows even more serious when such drives are used in small-size recorders equipped with only one motor. It should be noted, moreover, that the controlling of the recorder, by means of keys or buttons which have to produce a shift of the mechanical linkage by overcoming certain resistances, may be a source of inconvenience because an appreciable physical effort must be exerted.